High efficiency direct contact heat exchanger

ABSTRACT

A direct contact heat exchanger assembly is provided. The direct contact heat exchanger includes an evaporator jacket and an inner member. The inner member is received within the evaporator jacket. A sleeve passage is formed between the evaporator jacket and the inner member. The sleeve passage is configured and arranged to pass a flow of liquid. The housing has an inner exhaust chamber that is coupled to pass hot gas. The inner member further has a plurality of exhaust passages that allow some of the hot gas passing through the inner exhaust chamber to enter the flow of liquid in the sleeve passage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to U.S. Provisional Application Ser. No. 61/664,015, titled APPARATUSES AND METHODS IMPLEMENTING A DOWNHOLE COMBUSTOR, filed on Jun. 25, 2012, which is incorporated in its entirety herein by reference.

BACKGROUND

Thermal stimulation equipment used for generating steam or a gas from a liquid such as, downhole steam generator systems, high pressure chemical processing systems, purification and cleaning process systems, pumping equipment systems, etc, are subject to failure due to creep fatigue, corrosion and erosion. The primary source of corrosion is from dissolved solids, chlorine and salts that are released from boiling water. Another source of corrosion is from fuel (e.g. sulfur). A third source of corrosion is from an oxidizing agent (i.e. dissolved oxygen that may create rust). A primary source of erosion is from high velocity water and gas and a secondary source is from particulates from the supply lines.

The effectiveness of downhole steam generators is directly related to its ability to provide high quality steam. The length required for heat exchange is an essential issue related to the length of the tool and as a consequence the cost of steam generator and complexity of installation. Providing this high quality steam as close as possible to the formation being stimulated is a critical issue driving the efficiency of the downhole steam generator system.

For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an evaporator configuration that provides steam that is effective, efficient and robust to limit downhole stimulation equipment from fatigue, corrosion and erosion.

SUMMARY OF INVENTION

The above-mentioned problems of current systems are addressed by embodiments of the present invention and will be understood by reading and studying the following specification. The following summary is made by way of example and not by way of limitation. It is merely provided to aid the reader in understanding some of the aspects of the invention.

In one embodiment, a direct contact heat exchanger assembly is provided. The direct contact heat exchanger includes an evaporator jacket and an inner member. The inner member is received within the evaporator jacket. A sleeve passage is formed between the evaporator jacket and the inner member. The sleeve passage is configured and arranged to pass a flow of liquid. The housing has an inner exhaust chamber that is coupled to pass hot gas. The inner member further has a plurality of exhaust passages that allow some of the hot gas passing through the inner exhaust chamber to enter the flow of liquid in the sleeve passage.

In another embodiment, another direct contact heat exchanger assembly is provided. This direct contact heat exchanger assembly includes an elongated cylindrical evaporator jacket, a cylindrical inner member, and a plurality of raised fins. The cylindrical inner member is received within the evaporator jacket. The inner member has an inner surface that defines an inner exhaust chamber. The inner member is configured and arranged to pass hot gas through the inner exhaust chamber. An outer surface of the inner member and an inner surface of the evaporator jacket are spaced to form an annulus shaped sleeve passage that extends around the outer surface of the inner member. The sleeve passage is configured and arranged to pass a flow of liquid. The inner member has a plurality of exhaust passages that extend from the inner exhaust chamber into the sleeve passage. The exhaust passages allow at least some of the hot gas passing in the inner exhaust chamber to mix with the liquid passing in the sleeve passage to create a gas mix in the sleeve passage. The plurality of raised fins each extend out from the outer surface of the inner member within the sleeve passage to cause the flow of liquid to take a swirling path in the sleeve passage.

In another embodiment, a method of forming a direct contact heat exchanger is provided. The method comprises passing a body of liquid through a passage and injecting hot gas into the moving body of liquid in the passage.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more easily understood and further advantages and uses thereof will be more readily apparent, when considered in view of the detailed description and the following figures in which:

FIG. 1 is a side perspective view of direct contact heat exchanger assembly of one embodiment of the present invention;

FIG. 2 is a close up side view of a portion of the direct contact heat exchanger assembly of FIG. 1; and

FIG. 3 is a close up view of another portion of the direct contact heat exchanger assembly of FIG. 1.

In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the present invention. Reference characters denote like elements throughout Figures and text.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the inventions may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the claims and equivalents thereof.

Embodiments of the present invention provide an evaporator assembly that works with a downhole combustor. The evaporator assembly utilizes swirling water to provide a robust evaporator assembly that generates steam or other high vapor fraction fluid. The steam would then be injected into a reservoir for the production of hydrocarbons or utilized to provide energy into a downstream mechanism. Referring to FIG. 1, an evaporator assembly 100 of one embodiment is illustrated. The evaporator assembly 100 includes a jacket 102 that encases the evaporator. The evaporator assembly 100 is positioned between a combustor 200 positioned at an intake end 100 a of the evaporator assembly 100 and an optional radial support portion 300 that is positioned at an exit end 100 b of the evaporator assembly 100. The hot gas generator 200, in an embodiment, provides a fuel rich combustion. An example of a combustor 200 is illustrated in commonly owned patent application, U.S. patent application Ser. No. 13/745,196 filed on Jan. 18, 2013 entitled DOWNHOLE COMBUSTOR which is herein incorporated in its entirety by reference and the combustor described in U.S. Provisional Application Ser. No. 61/664,015, titled “APPARATUSES AND METHODS IMPLEMENTING A DOWNHOLE COMBUSTOR,” filed on Jun. 25, 2012. The combustor 200, in an embodiment, includes an initial ignition chamber (secondary chamber) and a main combustion chamber. The combustor 200 takes separate air and fuel flows and mixes them into a single premix air/fuel stream. The momentum from a premix injection stirs the ignition chamber at extremely low velocities relative to the total flow of air and fuel through the combustor 200. Diffusion and mixing caused by the stirring effect changes the initial mixture of the air/oxidant (air/fuel) to a premixed combustible flow. This premixed combustible flow is then ignited by one or more glow plugs. Insulated walls limit heat loss therein helping to raise the temperature of the premixed gases. Once the gases reach the auto-ignition temperature, an ignition occurs. This ignition acts as a pulse sending a deflagration wave into the main combustor chamber of the combustor 200 therein igniting the main flow field. Once this is accomplished, the one or more glow plugs are turned off and the initial ignition chamber no longer sustains combustion. One benefit to this system is that only a relatively small amount of power (around 300 Watts) is needed to heat up the glow plugs at a steady state. The combustion product of the combustor 200 is used by the evaporator assembly 100 to heat water to generate steam as described below.

In FIG. 1, the jacket 102 of the evaporator assembly 100 is shown as transparent so the inner assembly is illustrated. The jacket 102 provides protection for the inner assemblies. The inner assemblies of the evaporator assembly include a cylindrical inner member 111 with includes a turning vane 114 and a stator 116. The turning vane 114 and the stator 116 are positioned between the combustor 200 and a radial support 300. The stator 116, in this embodiment, includes a first stator portion 116 a, a second stator portion 116 b and a third stator portion 116 c. The first stator 116 a is cylindrical in shape and has a first diameter. The second stator 116 b is also cylindrical in shape and has a second diameter. The third stator 116 c is also cylindrical in shape and has a third diameter. The third diameter of the third stator 116 c is less than the second diameter of the second stator 116 c and the second diameter of the second stator 116 b is less than the first diameter of the first stator 116 a. The stator portions 116 a, 116 b and 116 c are separated from each other by reducers 104 a and 104 b that provide a reduction passage between the respective first, second and third stators 116 a, 116 b and 116 c. The reduction of the diameter of the stators 116 a, 116 b and 116 c, in this embodiment, corresponds to an increase in distance from the combustor which reduces the pressure required to drive the flow through the evaporator as discussed further below.

Close up views 108 and 110 of FIGS. 2 and 3 further illustrate portions of the evaporator assembly 100. In particular, portion 108 of FIG. 2, illustrates a portion of the evaporator assembly 100 next to the combustor 200. As illustrated in the close up view 108, the evaporator assembly 100 includes the outer evaporator jacket 102 that protects the system. The assembly 100 includes an inner exhaust chamber 118 in which the combustor exhausts combustion product 130. Defining the inner chamber 118 includes a cylindrical turning vane portion 114 and the cylindrical stator 116. Also illustrated is an outer sleeve passage 115 that is annular in shape that is formed between the evaporator jacket 102 and the turning vane 114 and stator portions 116 a, 116 b and 116 c.

Further leading from the combustor 200 in a collar 112. Water 120 pumped into the assembly 100 passes out under the collar 112 and into the sleeve passage 115. As discussed above, the turning vane 114 is cylindrical in shape. The turning vane 114 has a plurality of elongated outer extending raised directional turning fins 119. The raised directional turning fins 119 are shaped and positioned to direct the flow of water 120 passing under the collar 112. In particular, the raised directional turning fins 119 of the turning vane 114 direct the flow of water 120 into a helical path in the sleeve passage 115. In one embodiment, the directional turning fins 119 include a curved surface 119 a that extends along its length to direct the helical flow of water 120 in the sleeve passage 115. This helical flow path (swirl flow) in the sleeve passage 115 is maintained with the stator portion 116 as described below. The swirl flow causes a centrifugal force such that the water to act as a single body forced against the outer wall, .e.i, no individual droplets of water are able to form. The swirl flow further prevents the water from pooling in areas due to gravitational effects which can cause an uneven thermal distribution throughout the evaporator assembly 100 potentially reducing its useful life. The swirl angle is set such that the centrifugal force generated is able to overcome gravity based on the total throughput in the tool.

The stator 116 extends from the turning vane 114 and is also cylindrical in shape with reducer sections 104 a and 104 b as discussed above. The stator portions 116 a, 116 b and 116 c each include a plurality of elongated outer extending directional maintaining fins 117 that are designed to preserve the swirl flow of water and vapor started by the directional turning fins 119 of the turning vane 114 in the sleeve passage 115. At least one of the stator portions 116 a, 116 b and 116 c includes a plurality of exhaust passages 132 that extend from the inner chamber 118 to the sleeve passage 115. The exhaust passages 132 provide an effluent path for the combustion product 130 from the inner chamber 118 to the sleeve passage 115. The exhaust passages 132 are angled to enhance and maintain the helical flow path in the sleeve passage 115. Some of the combustion product 130 (exhaust from the combustor 200) passes through the exhaust passages 132 and heats up the water 120 flowing in the sleeve passage 115. The water 120, in response to the hot combustion product 130, turns into a steam mix 125 in the sleeve passage 115 that continues in the swirl pattern. As stated above, the exhaust passages 132 are angled to aid and maintain the helical flow path of the water 120/steam mix 125. In one embodiment, at least some of the exhaust passages 132 pass out an end of a respective directional maintaining fin 117 of the stator portion 116. As illustrated in FIG. 2, a directional maintaining fin 117 has a length defined between a first end 117 a and an opposed second end 117 b. The first end 117 a in this embodiment is rounded to minimize friction encountered by the steam mix 125 as the steam mix 125 flows in the spiral pattern in the sleeve passage 115. Moreover, in this embodiment, the first end 117 a of the directional maintaining fin 117 is wider than the second end 117 b of the directional maintaining fin 117 to enhance flow. An exhaust passage 132, in an embodiment, is positioned to extend out of the second end 117 b of the directional maintaining portion 117.

Referring to FIG. 3, a close up view of section 110 of the evaporator assembly 100 of FIG. 1 is illustrated. This exit end 100 b of the evaporator assembly 100 illustrates where the combustion product 130 and steam mix 125 exit the evaporator assembly 100. As illustrated, an end portion 150 extends from the stator 116. The end portion 150 is generally cylindrical in shape to maintain the inner chamber 118 and the sleeve passage 115. The end portion 150 includes an inner surface 151 that is as wide as an inner surface of the stator 116 but narrows as it extends to an orifice end cap 162. Hence, the inner chamber 118 narrows as it reaches the end cap 160. The end cap 160 includes a central opening 162 in which the combustion product 130 leaves the evaporator assembly 100. Within the orifice end cap 160 is housed a orifice member 190 that includes an orifice passage 191 that leads from the inner chamber 118 to the central opening 162 of the end cap 160. The orifice member 190 creates a back pressure. This backpressure is used to increase the flow rate to the upstream portions of the tool at low flow rates. At high flow rates this orifice member relieves backpressure so that the structural integrity of the evaporator meets its life requirements for operation. The end portion 150 further includes an outer surface that includes a first portion 152 a and a second portion 152 b. The first portion 152 a of the outer surface 152 of the end portion 150 is positioned next to the stator portion 116. The second portion 152 b has a smaller diameter than the first portion 152 a of the outer surface 152 of the end portion 150 such that a shoulder 153 is formed between the first portion 152 a and the second portion 152 b of the outer surface 152 of the end portion 150. A thermal growth spring 170 is positioned over the second portion 152 b of the outer surface 152 of the end portion 150. The thermal growth spring 170 has a first end 170 a that engages the shoulder 153 in the outer surface 152 of the end portion 150. A second end 170 b of the thermal growth spring 170 engages a portion of the radial support 300. The thermal growth spring 170 allows the stator assembly to transmit structural loads of transportation and handling while providing the flexibility to relieve thermal growth once downhole and in operation which reduces the propensity for creep fatigue failures. Also illustrated in the embodiment of FIG. 3, is a first centering spring 180. The first centering spring 180 is received in an inner groove 181 in the radial support 300. The first centering spring 180 further engages the second portion 152 b of the outer surface 152 of the end portion 150 to help position the end portion 150 in relation to the radial support 300 in order to effectively transfer loads from 150 to 300 while allowing relative motion along the longitudinal axis. Also illustrated is a second centering spring 182. The second centering spring 182 is received in a groove 183 in the end cap 162. The second centering spring 182 is engaged with an outer surface of the orifice portion 190. The second centering spring 182 helps position the orifice portion 190 in relation to the end cap 160 and relieve thermal growth of the orifice. As illustrated in FIG. 3, the steam mixture 125 exits the evaporator assembly 100 via the sleeve passage 115 which extends to an exit end 100 b of the evaporator assembly 100.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof. 

1. A direct contact heat exchanger assembly comprising: an evaporator jacket; and an inner member received within the evaporator jacket, a sleeve passage formed between the evaporator jacket and the inner member, the sleeve passage configured and arranged to pass a flow of liquid, the housing having an inner exhaust chamber coupled to pass hot gas, the inner member further having a plurality of exhaust passages that allow some of the hot gas passing through the inner exhaust chamber to enter the flow of liquid in the sleeve passage.
 2. The direct contact heat exchanger assembly of claim 1, further comprising: the evaporator jacket being elongated and generally cylindrical in shape; and the inner member including, a generally cylindrical turning vane received within the evaporator jacket, the turning vane having an inner surface that defines at least part of the inner exhaust chamber, the turning vane coupled to pass hot fluid through the inner exhaust chamber, an outer surface of the turning vane and an inner surface of the elongated jacket are spaced to form at least in part the sleeve passage that is annulus shaped and extends around the outer surface of the turning vane, the turning vane having a plurality of elongated raised directional turning fins that extend out from the outer surface of the turning vane within the sleeve passage, the turning fins positioned to direct a flow of water in the sleeve passage into a swirling path around the inner exhaust chamber, and a generally cylindrical stator received within the evaporator jacket, the stator coupled to the turning vane, the stator having an inner surface configured and arranged to form at least a part of the inner exhaust chamber, the stator having an outer surface, the outer surface of the stator and the inner surface of the elongated jacket are spaced to form at least a part the sleeve passage, the stator having a plurality of elongated outer extending directional maintaining fins that extend out from the outer surface of the stator within the sleeve passage to maintain the swirling path started by the turning fins of the turning vane, the stator having the plurality of exhaust passages that extend between the inner exhaust chamber and the sleeve passage.
 3. The direct contact heat exchanger assembly of claim 2, wherein each turning fin includes a curved surface configured and arranged to direct the flow of fluid in the swirling path in the sleeve passage.
 4. The direct contact heat exchanger assembly of claim 2, wherein at least one of the directional maintaining fins further includes a length defined between a first end and a second end, the first end being rounded to minimize losses of the spiral flow, the second end of the directional maintaining fin having an opening to one of the exhaust passages.
 5. The direct contact heat exchanger assembly of claim 2, wherein at least one of the exhaust passages extends through a portion of an associated directional maintaining fin on the stator.
 6. The direct contact heat exchanger assembly of claim 2, further comprising: a cylindrical end portion having a first end coupled to the stator, the end portion received within the evaporator jacket, the end portion having an inner surface that forms in part the inner exhaust chamber, the end portion further having an outer surface, the outer surface of the end portion spaced a distance from the evaporator jacket to form in part the sleeve passage, the end portion further having a second end, the inner surface having a narrower diameter at the second end than a diameter at the first end of the end portion.
 7. The direct contact heat exchanger assembly of claim 6, further comprising: the outer surface of the end portion having a shoulder; a thermal growth spring having a first end and a second end, the first end of the thermal growth spring engaging the shoulder of the end portion; and a radial support in communication with an end of the evaporator jacket, the second end of the thermal growth spring engaging a portion of the radial support.
 8. The direct contact heat exchanger assembly of claim 6, further comprising: an orifice end cap coupled to the second end of the end portion, the orifice end cap having a central opening in which combustion product can pass out of the inner exhaust chamber; and an orifice member received within the end cap, the orifice member having an orifice passage that leads from the inner exhaust chamber to the central opening of the end cap, the orifice member creating back pressure.
 9. The direct contact heat exchanger assembly of claim 2, wherein the stator further comprises: at least a first and a second stator portion, the first stator portion having a first diameter, the second stator portion having a second different diameter; and at least one reducer coupling the first stator having the first diameter to the second stator portion having the second diameter.
 10. A direct contact heat exchanger assembly comprising: an elongated cylindrical evaporator jacket; a cylindrical inner member received within the evaporator jacket, the inner member having an inner surface that defines an inner exhaust chamber, the inner member configured and arranged to pass hot gas through the inner exhaust chamber, an outer surface of the inner member and an inner surface of the evaporator jacket are spaced to form an annulus shaped sleeve passage that extends around the outer surface of the inner member, the sleeve passage configured and arranged to pass a flow of liquid, the inner member having a plurality of exhaust passages that extend from the inner exhaust chamber into the sleeve passage, the exhaust passages allowing at least some of the hot gas passing in the inner exhaust chamber to mix with the liquid passing in the sleeve passage to create a gas mix in the sleeve passage; and a plurality of raised fins extending out from the outer surface of the inner member within the sleeve passage to cause the flow of liquid to take a swirling path in the sleeve passage.
 11. The direct contact heat exchanger assembly of claim 10, wherein at least some of the exhaust passages pass through an associated fin.
 12. The direct contact heat exchanger assembly of claim 10, wherein the plurality of raised fins further comprises: a plurality of elongated raised directional turning fins extending out from the outer surface of the inner member within the sleeve passage, the turning fins positioned to direct the flow of liquid in the sleeve passage into the swirling path around the inner member; and a plurality of elongated outer extending directional maintaining fins that extend out from the outer surface of the inner member within the sleeve passage to maintain the swirling path started by the directional turning fins,
 13. The direct contact heat exchanger assembly of claim 12, wherein each turning fin includes a curved surface configured and arranged to direct the flow of water in the swirling path in the sleeve passage.
 14. The direct contact heat exchanger assembly of claim 12, wherein at least one of the directional maintaining fins further includes a length defined between a first end and a second end, the first end being rounded to help maintain the spiral flow, the second end of the directional maintaining fin having an opening to one of the exhaust passages.
 15. The direct contact heat exchanger assembly of claim 10, further comprising: a cylindrical end portion having a first end coupled to the stator, the end portion received within the evaporator jacket, the end portion having an inner surface that forms in part the inner exhaust chamber, the end portion further having an outer surface, the outer surface of the end portion spaced a distance from the evaporator jacket to form in part the sleeve passage, the end portion further having a second end, the inner surface having a narrower diameter at the second end than a diameter at the first end of the end portion; the outer surface of the end portion having a shoulder; a thermal growth spring having a first end and a second end, the first end of the thermal growth spring engaging the shoulder of the end portion; and a radial support in communication with an end of the evaporator jacket, the second end of the thermal growth spring engaging a portion of the radial support.
 16. The direct contact heat exchanger assembly of claim 15, further comprising: an orifice end cap coupled to the second end of the end portion, the orifice end cap having a central opening in which combustion product can pass out of the inner exhaust chamber; and an orifice member received within the end cap, the orifice member having an orifice passage that leads from the inner exhaust chamber to the central opening of the end cap, the orifice member creating back pressure.
 17. The direct contact heat exchanger assembly of claim 10, wherein the inner member further comprises: a generally cylindrical turning vane, plurality of elongated raised directional turning fins extending out from an outer surface of the turning vane within the sleeve passage; and at least one generally cylindrical stator coupled to the turning vane, the plurality of elongated outer extending directional maintaining fins extending out from an outer surface of the at least one stator within the sleeve passage to maintain the swirling path started by the turning fins of the turning vane.
 18. The direct contact heat exchanger assembly of claim 17, wherein the at least one stator further comprises: at least a first and a second stator portion, the first stator portion having a first diameter, the second stator portion having a second different diameter; and at least one reducer coupling the first stator having the first diameter to the second stator portion having the second diameter.
 19. A method of forming a direct contact heat exchanger, the method comprising: passing a body of liquid through a passage; and injecting hot gas into the moving body of liquid in the passage.
 20. The method of claim 19, further comprising: causing the body of liquid to swirl through the passage.
 21. The method of claim 19, further comprising: passing the hot gas through an inner exhaust chamber; swirling the body of liquid around the inner exhaust chamber in a sleeve passage; and injecting the hot gas into the moving body of liquid through a plurality of exhaust passages that lead from the inner exhaust chamber to the moving body of liquid.
 22. The method of claim 21, wherein swirling the body of liquid around the inner exhaust chamber in a sleeve passage further comprises: engaging the body of liquid with elongated raised directional turning fins positioned within the sleeve passage to direct the liquid to flow in a helical flow pattern around the inner exhaust chamber.
 23. The method of claim 21, further comprising: creating back pressure in the inner exhaust chamber.
 24. The method of claim 21, further comprising: thermally extending the length of the sleeve passage. 